Photo-receiving device with light guide

Abstract

A high-speed, high-sensitivity photo-receiving device has a light-absorbing substrate, on which a pair of electrodes are provided. An insulative optical guide is located over an exposed surface portion of the substrate constituting an optical window. The optical guide is permeable to incident light, and the width of the optical guide does not exceed the wavelength of the incident light.

What is claimed is: 
     
       1. A photo-receiving device, comprising; a light absorbing substrate,   a pair of electrodes disposed on a surface of the light-absorbing substrate,   an optical window through which light to be detected enters, said optical window being an exposed surface portion of the substrate between the electrodes, and   an optical guide provided on the exposed surface of the portion of the substrate between the electrodes, said optical guide comprising a single material being permeable to the light to be detected, having a width that does not exceed a wavelength of the light to be detected and a thickness greater than a thickness of said pair of electrodes, and exhibiting a higher resistance than that of the substrate.   
     
     
       2. A photo-receiving device according to claim 1, wherein the optical guide is formed of a semiconductor. 
     
     
       3. A photo-receiving device according to claim 1, comprising: a top surface of said optical guide being directly exposed to said light.   
     
     
       4. A photo-receiving device according to claim 1, comprising: said electrodes disposed in contact with respective side surfaces of said optical guide.   
     
     
       5. A photo-receiving device according to claim 1, comprising: said optical window being defined by said electrodes.   
     
     
       6. A photo-receiving device according to claim 5, comprising: said optical window having said width.   
     
     
       7. A photo-receiving device according to claim 1, comprising: said substrate being a GaAs-based material.